import java.util.Arrays;

public class HashBuck2<K,V> {
    static class Node<K,V> {
        public K key;
        public V val;
        public Node<K,V> next;
        public Node(K key, V val) {
            this.key = key;
            this.val = val;
        }
    }

    public Node<K,V>[] array = (Node<K, V>[])new Node[10];
    public int usedSize;
    public static final double LOAD_FACTOR = 0.75;

    public void put(K key, V val) {
        int hash = key.hashCode();
        int index = hash % array.length;
        Node<K,V> cur = array[index];
        while(cur != null) {
            if(cur.key.equals(key)) {
                cur.val = val;
                return;
            }
            cur = cur.next;
        }
        Node<K,V> node = new Node<>(key, val);
        node.next = array[index];
        array[index] = node;
        usedSize++;
        if(calculateLoadFactor() >= LOAD_FACTOR) {
            //扩容
            resize();
        }
    }
    private void resize() {
        Node<K,V>[] newArray = new Node[2 * array.length];

        for (int i = 0; i < array.length; i++) {
            HashBuck2.Node<K,V> cur = array[i];
            while(cur != null) {
                HashBuck2.Node<K,V> curNext = cur.next;
                int hash = cur.key.hashCode();
                int index = hash % newArray.length;//找到了在新的数组当中的位置
                cur.next = newArray[index];
                newArray[index] = cur;
                cur = curNext;
            }
        }
        array = newArray;
    }

    //计算负载因子
    private double calculateLoadFactor() {
        return usedSize * 1.0 / array.length;
    }

    public V get(K key) {
        int hash = key.hashCode();
        int index = hash % array.length;
        Node<K,V> cur = array[index];
        while(cur != null) {
            if(cur.key.equals(key)) {
                return cur.val;
            }
            cur = cur.next;
        }
        return null;
    }

}
